1. Field of the Invention
The present general inventive concept relates to allocation of an Internet protocol (IP) address, and, more particularly, to a method of allocating an IP address of an image forming apparatus using the Dynamic Host Configuration Protocol (DHCP), an image forming apparatus to which an IP address is allocated using DHCP, and a system of allocating an IP address using DHCP.
2. Description of the Related Art
In general, a Dynamic Host Configuration Protocol (DHCP) server has a function of transmitting configuration parameters to a plurality of hosts using Transmission Control Protocol/Internet Protocol (TCP/IP). The DHCP allows a client to receive dynamic or static IP configuration information from the DHCP server when booted so that there is no need for a network manager to configure a network for each host, and allocates a number of IP addresses, which is smaller than the number of actually existing clients, so that a limited number of IP addresses can be efficiently used.
In the case of dynamic allocation of an IP address, when a configuration information request is received from a client, the network manager selects an IP address that is not currently allocated to any client from a predetermined range of predetermined IP addresses (for example, 100.1.1.1 through 100.1.1.254) and allocates the selected IP address to the client. Here, the DHCP server does not grant the client a right to use the IP address unlimitedly, but gives the client a right to use the IP address only for a predetermined period previously set by the network manager.
In the case of static allocation of an IP address, when a configuration information request is received from a client, the DHCP server confirms whether the hardware address of the client is included in a table constructed of pairs of IP addresses previously designated by the network manager and hardware addresses and allows the client to use IP configuration information unlimitedly only when the table includes the hardware address of the client.
When a network printing device, constituting a DHCP client, is turned off/on, the network printing device operates and requests the DHCP server to allocate an IP address thereto. In this situation, the DHCP server allocates an IP address other than the IP address previously allocated to the DHCP client to the DHCP client. This affects an IP address based network printing service. That is, even if a user simply turns off/on the network printing device, IP address configuration is changed and thus the user cannot use a desired service or has to reconfigure the IP address of the network printing device.